A hinge structure typically includes two hinge members which are rotatably secured together by a pin or the like. Automatically operated doors, such as those commonly used in shopping centers, schools, or the like, are continually operated and are substantially heavier and larger than those used in most homes. As will be understood, continual use of a door submits the hinge structure to extensive wear. Notwithstanding their continual use and the substantial loads placed thereon, a hinge structure is expected to perform error-free and with minimum maintenance.
Increases in height and/or weight of the door, or the like, carried by the hinge member, adds to the frictional sliding contact between the hinge members and thereby increases the wear on the hinge structure. As may be appreciated, and despite the wear on such hinge structures, the hinge members are not normally permitted to longitudinally move relative to each other during their operation.
My U.S. Pat. No. 3,092,870 dated June 11, 1963, discloses a pinless hinge structure offering increased performance and durability. Such a hinge structure includes two longitudinally extending hinge members which are rotatably joined along adjacent longitudinal edges by intermeshing gear segments forming part of the hinge members and which define a hinge joint. A clamp member maintains the gear segments in mesh relative to each other while permitting smooth and uniform movement of the hinge members through a full arc of travel of the hinge. The clamp member has a generally C-shaped cross section whose inwardly turned ends are formed with longitudinally extending rod-like portions. Each rod-like portion on the clamp member fits within a longitudinal channel formed in the gear segment and defines a fixed axis of rotation for each hinge member.
The design and performance of the hinge structure disclosed in the above-identified patent was further enhanced through the provision of a longitudinal thrust bearing which was the subject of my U.S. Pat. No. 3,402,422 dated Sept. 24, 1968. My patented longitudinal thrust bearing comprises a solid bearing member disposed in longitudinally co-extensive recesses formed in adjacent longitudinal edges of each rotatable hinge member for inhibiting longitudinal movement of one hinge member with respect to the other hinge member. Preferably, several thrust bearing assemblies are longitudinally spaced along the length of the door to distribute their load bearing capability.
For appearance and privacy, buildings are frequently provided with self-closing cabinets and other closures. Moreover, fire safety doors on buildings are commonly designed with a self-closing feature. Therefore, there is both a need and a desire for hinge structures which impart a self-operating feature to the door, or the like, mounted thereon.
Electrical alarm systems are commonly used for monitoring whether a door is secured and/or the relative angular position thereof. Such alarm systems typically include a separate conduit or wire which bridges the rotatable hinge joint between the hinge members. Moreover, some door-mounted, electrically operated mechanisms such as locks, panic bars, automatic actuators, and the like, typically require high-level electric current to be passed across the rotatable hinge joint of a hinge structure to operate such mechanisms. To combine the ability to transmit electrical power across a rotatable hinge joint of a hinge structure with the above-described self-operating feature would simplify the hinge structure design and would furthermore lessen the parts required to effect such ends and, thereby, advantageously reduce the hinge structure costs.